Q: My cousin was diagnosed with a disease called PML and they said it was due to the Jesus Christ virus. Is there really a virus called the Jesus Christ virus and how does it cause PML?

A: Infection with the John Cunningham virus (JC virus, named after the first patient from which the virus was isolated), a polyomavirus virus and sometimes colloquially referred to as the "Jesus Christ" virus because of the initials, is extremely common; antibodies to this virus, demonstrating prior exposure, are present in more than three quarters of adults. Although it is not clear how the virus is transmitted, it is thought to be acquired during childhood, causing minimal (likely "cold-like") or no symptoms. The virus is then thought to go through the bloodstream and possibly settle in the kidneys and/or the lymphoid organs (lymph nodes, spleen, gastrointestinal tract lymphoid tissue, others), where it may lie quiescently.

In patients with compromised immune systems (such as those with AIDS, those on immune-suppressant medications for conditions such as organ transplants, multiple sclerosis, systemic lupus erythematosus, certain cancers such as lymphoma or those with certain other diseases) the JC virus can reactivate and in some cases make its way to the brain. Progressive multifocal leukoencephalopathy (PML) is due to the JC virus infecting the cells that produce the outside covering (the myelin) of axons (the long thin projections from the nerve cell that conducts the electrical signals) as well as the cortical neurons (the nerves that control thought, voluntary movement and perception), causing inflammation and cell destruction.

In the past PML used to affect up to 5 percent of HIV patients, but with HAART (highly active antiretroviral therapy) the incidence of this condition in AIDS patients has significantly decreased. PML affects anywhere from one in 1000 to one in 100 patients whose immune systems are compromised for reasons other than AIDS.

PML may affect different areas (hence the "multifocal" part of the condition’s name) of the brain (typically the white matter regions of the brain, hence the "leuko," meaning "white," part of the name) and hence cause different symptoms in different patients. Symptoms of PML are progressive (typically over weeks to months, and hence the ‘progressive’ part of the name) and may include encephalopathy symptoms (explaining the last part of the name progressive multifocal leukoencephalopathy) such as clumsiness, weakness, seizures, difficulty walking, changes in personality and/or behavior, vision and/or speech problems. These symptoms can become very severe, and around 30 to 50 percent of PML patients die of the disease within a few months of diagnosis, with a large percentage of the survivors suffering permanent disabilities.

PML is suspected based on the symptoms and risk factors. Imaging tests of the brain, such as CT or MRI, can further support the diagnosis. Examination of the cerebral spinal fluid in PML patients will demonstrate the JC viral infection to corroborate the diagnosis. In some cases where the diagnosis is in doubt and no other cause of the symptoms is identified, a brain biopsy may be indicated.

Page 2 of 2 - At the present time there is no specific therapy for PML. The first step in treatment is to address the immune deficiency, typically by discontinuing immune-suppression medications and in AIDS patients increasing the aggressiveness of HIV treatments (HAART). In some patients steroid medications may be used to address inflammation, but as these medications may further suppress the immune system this treatment must be utilized with care. Some new drugs that have shown promise treating the JC virus, such as Hexadecyloxypropyl-Cidofovir (CMX001), are being evaluated.

Patients with weakened immune systems should be closely monitored for signs and symptoms possibly suggestive of PML. Research is being done to develop new and more specific treatments, and hopefully these future treatments will improve the prognosis for people with this condition.